Electric motor-drive.



@ 10 841,270: W B POTT R PATENTED JAN. 15, 1907.

ELECTRIC MOTOR DRIVE.

APPLICATION FILED MAR-21.1904.

UNITED srarns Pars-hr OFFICE ILLIAM B. POTTER, or scnnracranr, NEW roan, ASSIGNOR To GE aRAL ELECTRIC coMPANY; A 'ooaronarionfor ,Nnw roan.

To all whom. it may concern:

Be it known that 1, WILLIA B. POTTER,

a citizen of the United States, residing at Schenectady, in the county of Schenectady and State of New York, have invented certain new and .useful Improvements in Electric Motor-Drives, of which. the' following is a specification. r

' My invention relates to electric motordrives,,and has particular reference to electric drives for 'machines in which it is desirable thatthe speed should increase with the creased lift, but it is also necessary that'the speed of the pump should be increased in order to accomplish the necessary lift.

Two arrangements of motor-drive that are well known in theart and thatmay be arranged to give increasing speed with increas ing output are the difl erentially-wound motor and the shunt-motor with series booster. Such devices are described in Patent No. 555,191, Thomson, dated February 25, 1896. Both of these devices, however, are unstable on heavy loads, tending to race and heavily overload themselves. To meet this difliculty, the Thomson patent describes an arrangement of the booster-field such that it becomes saturated on'heavy loads.

My invention consists in the combination of a shunt-motor and. a differential booster in series with it, the series Winding of the booster normally predominating, and the, shunt-whirling serving to limit the boostervoltage at high speeds, and consequentlyto prevent racing. I

Myinvention will best be understoodby reference to the accompanying drawing, which shows somewhat diagrammatically a motor-drive arranged in accordance with my invention.

.C represents; a rotary pump taking water from the suction-pipe S and delivering it through the delivery-pipe D. Rotary pump C is driven by the shunt-motor M, the shuntfield F of which isconnected across the con- Specification of Letters Patent. Application filed March 21, 1904:. Serial No. 199.161.

--parts here shown, but aimin the a cla ms to cover all modifications W ch are ELECTRIC MGTQR DRiX/E.

Patented an. 15, 1907;

stant potential source ofsupply 1 2. The

armature A of motor M is connected. to line wire? through the usual starting-rheostat R and is connected to line-wire 1 through the differential booster B, the armature at of which is mounted on the shaft" of motor M.

The differential booster B has its armature a and series fieldf connected in-serieswith armature A of motor M. Booster B also has a shunt field f connected across the terminals of its armature-c.

duce this voltage.

The two fields are so proportioned that under normal operation of motor A the shuntfieldfis overpowered and the booster B acts as a series booster, impressing an increasing voltage on the terminals of the shunt rnotor with increasing output, and thereby increasing the speed. The shunt-field serves merely to limit' the booster effect of the machine and becomespredominant only at highs eeds. The reason for the varying relative in uence of the series and shunt fields will be understood'when the effect of speed variations on these two fields is taken into consideration. The strength of the series field is not affected directly by the speed, but is determined always wholly by the current flowing through the, booster and is affected by the speed only as the speed affects the output. The shuntfield, on the other hand, is dependent upon the induced armature voltage in the booster, which depends upon-the product of the speed and the resultant booster field, and conse quently increases with increase of s ,eed

much more rapidly than the series eld. Therefore the two windings may readily be so proportioned that the shunt-field exerts a very small influenceunder normal operation, but comes into play effectively to imit the maximum speed of the motor, so as to pre'-- vent racing and serious overloading.

I do not desire to limit myself to the particular construction and arrangement of pended within the scope of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination, a shunt-motor, a memberdriven thereby, and-a differential booster The series field of the booster is properly connected so as to increase. the voltage impressed upon the armature A, while the shunt-field is wound to redriven by said inotor having its shunt-field connected. directly in shunt. to its armature and adapted to raisethe voltage imressed on said motor'upto a certain limit as t e load onsaid motor 'increases. Y 4 v- 2'. In combination, a shunt-motor, a member driven thereby, and a differential booster driven by saidmotor and connected in-series with the armaturepf said motor, said booster shunt to its armature.

- 3. In combination, a shunt-motor, a memhaving" its shunt-field connected. directly in be; driven thereby, and a differential booster drivenby said motor and in series therewith and having its seriescoil connected to raise the voltage on the motor, and a shunt-field connecte directly in shunt to'its armature,

} "4; In combination, a shunt-motor, a member driven thereby, and a booster driven by said motorand having its':armature and a series field-winding. in series with the arma-' tnre of said m'ot'o'r and connected to increase the voltagenpon said armature, and having a shunt-field connected across the boosterarmaturein opposition to the series field to jlifiiit-the increase of voltage.

'- 5. 'Incombination, ashunt-motor, a member driven thereby, and a differential booster havin its armature and series field in series with t e armature of said motor and havingfgo' its shunt-field so connected as to increase in strength with increase of the booster voltage.

6. In combination, a shunt-motor, a member driven thereby, and a differential booster in series therewith havin its series coil connected to increase the v0 tage impressed on the motor-terminals, and having its opposing shunt-field so connected as to increase in stren th with increase of the booster voltage.

7. combination, a shunt-motor, a member-driven thereby, a differential booster in series therewith having its series coil proportioned to preponderate normally and connectedto increase the voltage impressed on the'motor, and ashunt-coil so connected as to increase in strength with increase of the booster voltage and proportioned to balance the series fiel when the boostervoltage increases to a certain limit.

. In witness whereof I havehereunto set my "50 

